Platinum diamine dichloride (variously, cis-platinum, cis-platin, platamine, etc.) has been used as a treatment for certain carcinomas (mainly prostatic) for several years, but suffers from the drawback of requiring large dosages which induce unpleasant side-effects (hair loss, nausea, anaemia, etc.). The compound is believed to work by forming stable complexes with DNA in cell nuclei. This prevents both transcription of the DNA, thus blocking protein synthesis, and replication of the DNA thus inhibiting mitosis. The treatment therefore is not specific for cancer cells only, but also affects cells which normally multiply (bone marrow, skin, gut epithelium, etc.), or synthesise proteins (e.g. liver). The apparent main reason for the high dosages required is the hydrophilic (lipophobic) nature of the compound, and thus the difficulty of its passage through the mainly lipid environment of cell membranes.
Certain unsaturated fatty acids have been shown to have much higher levels of toxicity towards cancer cells than normal cells. The mechanism for this is not clear, but is thought to relate to an impaired capability of cancer cells to metabolise fatty acids normally, and thus an inability to respond properly to exogenous dosage with such fatty acids. The position of the unsaturations in the hydrocarbon chain does not appear to be critical for the production of cytotoxic effects, with the proviso that such unsaturations are desirably methylene-interrupted and that desirably the first unsaturation is in the n-3, n-6, or n-9 position. The number of unsaturations does appear to matter however, with toxicity increasing with number of unsaturations. In general the configuration (cis or trans) of the unsaturations does not have much effect on cytotoxicity. Such fatty acids are obviously highly lipophilic and hydrophobic, thus the generation in vivo of levels high enough to facilitate cytotoxic effects is difficult.